Tanks and troops were on the streets of the capital of Guinea today amid confusion over whether the west African nation's military has seized power following the death of the country's long-serving authoritarian president, Lansana Conté.

Armed forces could be seen apparently heading for the prime minister's office inside the presidential palace in the country's capital, Conakry, a reporter for the Associated Press said after Guinea's civilian leaders rejected claims by the military that it had seized control. Reuters said other troops were guarding bridges in the city, which remained calm.

It was not know to whom the troops were allied. But they began to move shortly after the country's prime minister rejected claims of a successful coup to insist he remained in office.

The turmoil began with news that Conté had died after ruling for 24 years as only the second president in Guinea's half-century of independence. At 2am, the leader of the mineral-rich but impoverished west African nation's parliament, Aboubacar Somparé, appeared on TV alongside the head of the military to announce the president's death. Somparé said he should be named interim president, as laid down in the country's constitution. But less than six hours later, soldiers entered the headquarters of the state TV and radio services and forced journalists to broadcast a statement announcing a coup.

"The constitution is dissolved," said an officer identified as Captain Moussa Camara. "The government is dissolved. The institutions of the republic are dissolved."

From now on, the statement said, Guinea would be ruled by a so-called national council for democracy to tackle widespread corruption and a "catastrophic economic situation". The ousted government was "in large part responsible for this unprecedented economic and social crisis", said Camara, who did not say whether he was the coup leader or just a spokesman. He said presidential elections would be organised shortly and ordered citizens to stay at home.

Several hours later, the country's prime minister, Ahmed Tidiane Souaré, said he was was speaking from his office and that his government "continues to function as it should".

"I do not know these people who have spoken. We are trying to settle this question of national importance," he told Radio France Internationale. "I am sure that they will see reason. They have not used force. There has been no threat against anybody."

Somparé told France 24 television that it was "a minority of soldiers and officers" who had attempted the coup. "The vast majority is loyal," he said.

France, the country's former colonial ruler, said it did not believe the coup had succeeded. "It seems that the legitimate authorities are currently in control of the situation in the country," said Eric Chevallier, a spokesman for the foreign ministry in Paris. "We have a claim that does not seem to be backed up by the facts."

The coup was condemned by the African Union, which said it would hold an emergency meeting.

Guinea is the world's largest exporter of bauxite, the ore used in aluminium production, but rampant corruption and decades of economic mismanagement have seen very little of this wealth reach the country's 10 million people, who exist on an average annual wage of about £270.

Conté, who seized power in 1984 after the death of the first post-independence president, Ahmed Sékou Touré, faced regular unrest in the later years of his rule. Serious ill health made him increasingly reclusive and he travelled abroad regularly for treatment.

Two years ago, Guinea descended into street warfare as demonstrators demanded that Conté step down. He responded by sending tanks into the capital.

Conté began as a dictator but later allowed the formation of political parties, staging the country's first elections in 1993. He was elected to the presidency three times in all, although opponents and outside observer condemned the polls as flawed.

While he abandoned Touré's socialist-style economic policies, Conté made a poor job of managing the economy, and the former food-exporting country began to import food under his rule. His unpopularity was reflected in revolts by disgruntled soldiers and at least two attempts to oust him.

During the last election, rumours grew of his failing health. He was reportedly so ill that he did not even get out of the car to cast his ballot. That winter, he was forced to go on TV to put a stop to rumours of his death. "Everybody dies," he said. "Even the Prophet died. I will die when Allah wants me to."

More rumours began two weeks ago when Conté failed to make his usual TV appearance on the occasion of a major Muslim holiday. The prime minister and others hurried to make appearances in his place, but people were on edge and numerous businesses closed their doors in anticipation of unrest.

Last week, the editor of a local paper was arrested after publishing a picture of the frail leader struggling to stand up. The newspaper was ordered to print a different photograph of Conté showing him in good health.